Production of an alkali metal double fluoride of titanium



United States Patent P PRODUCTION OF AN ALKALI METAL DOUBLE FLUORIDEOF TITANIUM Eugene Wainer, Cleveland Heights, Ohio, assignor, by mesne assignments, to Horizons Titanium Corporation, Princeton, N. J., a corporation of New Jersey No Drawing. Application February 4, 1952, i Serial No. 269,695 r Claims. CI. 23-88 In the production and use of compounds of titanium,

and particularly the fluoride compounds, a serious disadcompactly workable process may be had, with elimination of losses heretofore serious. Other objects and advantages will appear from the following description.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In general, the invention involves cycling thealkali metal component for compound fluorides of titanium through zones reacting alkali metal fluoride with a titanium. compound to formation of double fluoride, and

, a zone decomposing such double fluoride to titanium metal and alkali fluoride, and then to such first reaction zone to form double fluoride. Thus, by-product alkali fluoride otherwise left by decomposing a double fluoride of titanium is recycled to the reaction zone forming double The titanium compounds as raw material for preparation of titanium double fluoride are such raw materials as ilmenite and other ores of titanium, more or less purified oxide of titanium, meta-titanic acids, slags containing high percentages of titanium dioxide, titanium sulfates, and the like. For the alkali metal fluoride component, it will be understood that this comprises metals of the alkali group, potassium and sodium being preferred, and the term alkali fluoride concisely designates all these hereinafter.

The double fluoride of titanium and alkali metal is subjected to decomposition in a decomposing zone to form titanium metal, and the alkali fluoride is a byproduct. While the decomposition of the double fluoride may be carried out by heat reaction, electrolysis is here more generally involved and in presence of chlorine, and as the details are not a part of the present invention, it is here suflicient to state that the compound fluoride of titanium and alkali metal as afore-mentioned, is decomposed to metallic titanium and fluorides such as of potassium and sodium. It is such latter material that is then recycled to the formation of double fluoride of titanium and alkali metal.

With a raw material such as ilmenite, a desirable procedure is to reduce the iron content to the ferrous state, either by heating in the presence of carbon (finely divided, or a reducing gas or reducing furnace atmosphere) or by addition of scrap iron and sulfuric acid. If the amount of the sulfuric acid is sufficient to react with all of the constituents of the ilmenite, there results titanium sulfate and iron sulfate solution. After such reaction is "ice completed, the solution is diluted and the insolubles such as silicates, etc., are removed by settling, decantation, filtration, and the like. To the combined titanium iron sulfate solution there is then admixed the alkali metal fluoride as from the afore-mentioned decomposition of double fluoride of titanium and alkali metal. Thus, where the decomposition has been in an electrolytic zone, the alkali fluoride remaining from the electrolysis is recycled to the zone reacting'titanium compound with alkali metal fluoride in the first instance. Usually, an electrolytic bath based on double fluoride of titanium, together with a molten bath constituent of halide, a chloride of alkali or alkaline earth metal (i. e., K, Na, Li, Sr, Ba, or mixtures, and preferably sodium chloride), after the electrolysis consists of potassium fluoride and sodium fluoride. Thus, with a bath in the first instance of potassium titanium fluoride and a sodium chloride bath component subjected to electrolysis, the decomposition may be generally represented by the following equation:

electrolysis lllustratively also, the reaction of sulfuric acid on the ilmenite as above-mentioned may be represented by the following equation:

2. FeO.TiO2+3H2SO4- Ti (S04 2+FeSO4+ 3H2O The combined titanium iron sulfate solution is treated with the constituents remaining from the decomposition or electrolysis, viz., the alkalimetal fluorides. Usually these will include sodium chloride which has not been In the presence of varying amounts of sodium chloride, somewhat better results are obtained if roughly two-thirds of the total fluorine requirement to make double fluoride, in the form of the mixed potassium sodium fluoride salts isfirst added to the titanium sulfate solution in dissolved 1 form, and then if any precipitate occurs it is removed by filtration. The reaction of the sulfuric acid on the ilmenite in the first instance, involves raised temperature, and to the clear hot liquor, after filtration, the remaining fluoride requirement is added. Reaction occurs, and then the solution is evaporated down until crystals appear, and potassium titanium fluoride thus separates out. This potassium titanium fluoride is then re-dissolved and recrystallized, and made up for electrolysis with further sodium chloride, and is again subjected to decomposition. Chlorine is evolved, but fluorine is not. Thus, the prooess is completely cyclical, and the only losses are the minor losses normally encountered in properly controlled chemical operation. Costly fluorine is conserved and cycled through the respective reaction zones.

Instead of operating batch-wise in decomposition for electrolysis of the double fluoride of titanium and alkali metal, in some cases a continuous type of operation may be applied, removing molten bath material from the reaction zone as the process proceeds, this being possible by reason of the fact that the titanium metal formed is segregated at the cathode.

Illustratively, then, with ilmenite as the starting material, the only raw materials which are consumed in the operation are ilmenite, sulfuric acid, and the sodium chloride or alkali metal halide bath component, and the entire operation may be summarized illustratively by the following equation:

4. FeO.TiO2l-3H2SO4+4NaCl- I In similar manner, other raw materials than ilmenite,

,and other alkali metal bath halide components apply in the same general way.

As an example: Ilmenite, finely ground, is reacted upon .with sulfuric acid solution in amount to substantially completely dissolve it. Any insolubles are eliminated. The

, reaction involves raised temperature, and to the clear hot solution, there is then added alkali metal fluorides, KF and NaF from the electrolysis of potassium titanium fluoride, in proportions of one mole of titanium sulfate and 2 until crystals begin to appear, and then on cooling, the

. potassium titanium fluoride separates out, and is removed by filtration. It is then re-dissolved and re-crystallized, I and mixed with sodium chloride in about the proportions And later with voltage increased to 5-8, and current density 200-500 amp., titanium metal sponge is deposited in a tightly adhering mass at the cathode, and the potassium fluoride isby-product for recycling to the production of potassium titanium fluoride.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

. 1. The method of producing an alkali metal fluotitanate .which comprises digesting an oxidicore of titanium in sulfuric acid to produce a solution containing titanium ions, effecting separation of any insoluble phase from the solution, reacting the said solution with a source of fiuo- Y ride ions and of alkali metal ions consisting essentially of the spent salt bath resulting from the electrolytic decomposition of an alkali metal fluotitanate in a fused alkali metal halide bath and crystallizing from said solution the resulting alkali metal fluotitanate.

2. The method of producing an alkali metal fluotitanate which comprises digesting ilmenite in sulfuric acid, efiecting separation of any insoluble phase from the resulting aqueous solution reacting the aqueous solution so obtained which comprises digesting an oxidic ore of titanium in sulmoles of potassium fluoride and 4 moles of sodium fluoride, with slight excess. The solution is then evaporated furic acid to produce a solution containing titanium ions, separating any insoluble phase from the solution produced, reacting the solution with a source of fluoride ions and potassium ions consisting esentially of the spent salt bath resulting from the electrolytic decomposition of potassium fluotitanate in a fused alkali metal halide bath and recovering potassium fiuotitanate from the resulting solution by crystallization.

4. The method of producing potassium fluotitanate from ilmenite which comprises reducing the iron content of the ilmenite to ferrous iron, digesting the resulting material in sulfuric acid to produce an aqueous solution containing titanium ions, separating insoluble materials therefrom, reacting the remaining aqueous solution with a source of fluorine ions and potassium ions consisting essentially of the spent salt bath resulting from the electrolytic decomposition of potassium fluotitanate in a fused alkali metal halide bath and recovering potassium fluotitanate from the resulting solution by crystallization therefrom.

5. The method of producing potassium fluotitanate from ilmenite which comprises reducing the iron content of the ilmenite to ferrous iron, digesting the resulting material in sulfuric acid to produce an aqueous solution containing titanium ions, separatiing any insoluble materials therefrom, reacting the remaining aqueous solution with a source of fluorine ions and potassium ions in the proportion of one mole of KF to two mols of NaF consisting essentially of the spent salt bath resulting from the electrolytic decomposition of potassium fluotitanate in a fused sodium chloride bath and recovering potassium fluotitanate from the resulting solution by crystallization therefrom- References Cited in the file of this patent UNITED STATES PATENTS Great Britain of 1904 

1. THE METHOD OF PRODUCING AN ALKALI METAL FLUOTITANATE WHICH COMPRISES DIGESTING AN OXIDE ORE OF TITANIUM IN SULFURIC ACID TO PRODUCE A SOLUTION CONTAINING TITANIUM IONS, EFFECTING SEPARATION OF ANY INSOLUBLE PHASE FROM THE SOLUTION, REACTING THE SAID SOLUTION WITH A SOURCE OF FLUORIDE IONS AND OF ALKALI METAL IONS CONSISTING ESSENTIALLY OF THE SPENT SALT BATH RESULTING FROM THE ELECTROYLTIC DECOMPOSITION OF AN ALKALI METAL FLUOTITANATE IN A FUSED ALKALI METAL HALIDE BATH AND CRYSTALLIZING FROM SAID SOLUTION THE RESULTING ALKALI METAL FLUOTITANATE. 